Synthesis and Evaluation of Diphenylpyrazine Cyclic Amine Derivatives as IP Receptor Agonists.

Background A major challenge with development of new targets for antithrombotic treatment is the sustained effect on the platelet and the target selectivity. While increasing cAMP in the platelet through activation of the prostacyclin (IP) receptor represents a viable antiplatelet target for prevention of thrombosis, current IP receptor agonists lack stability and selectivity. Development of a selective IP receptor agonist that is stable in the blood and selective for the IP receptor would represent a new approach for prevention of platelet activation and thrombosis in the blood and expand the utility of IP receptor agonists which are currently used for the treatment of pulmonary arterial hypertension (PAH). Purpose Develop an IV and oral IP receptor agonist, CS585, with sustained activity in vivo in the blood and eliminating the off-target effects observed with other IP agonists not having selective activation of the IP receptor. These characteristics would make CS585 an attractive new therapeutic approach for limiting platelet activation and thrombosis. Methods We assessed platelet activation and thrombosis in human blood ex vivo and mouse models in vivo. For mouse models, platelets and fibrin were labelled and accumulation at the site of injury was measured using intravital microscopy. Thrombosis in the vessel was assessed in the laser-induced cremaster thrombosis assay. Selectivity was assessed in human blood pharmacologically using prostaglandin receptor inhibitors and in mouse with an IP receptor knockout mouse. Flow cytometry, aggregometry, and western blot techniques were used to assess selectivity. Results IV and oral administration of CS585 resulted in sustained inhibited clot formation and fibrin formation at the site of injury in the laser-induced cremaster arteriole thrombosis assay in wild-type mice but was unable to alter platelet function in IP knockout mice. CS585 inhibition of platelet activation was fully prevented in platelets from IP knockout mice as assessed by flow cytometry (integrin activation and granule secretion) and by VASP phosphorylation. Inhibition of human platelet activation by CS585 was inhibited by pharmacological inhibition of the IP receptor, but not by inhibition of the DP1, EP2, or EP4 receptors as assessed by aggregation, flow cytometry, and VASP phosphorylation. Conclusions We have shown for the first time that CS585, a novel IP receptor agonist, not only inhibits platelet activation and clot formation, but gives sustained inhibition through multiple routes of administration in an in vivo mouse model of thrombosis. Importantly, the challenge in selectivity observed with other IP receptor agonists is not observed with CS585 supporting its development for a number of diseases in the cardiovascular system including thrombosis, VTE, secondary prevention after MI and stroke, and PAH.CS585 inhibition of thrombosis in vivoCS585 selectively signals through IP

A comparison of vasodilation mode among selexipag (NS-304; [2-{4-[(5,6-diphenylpyrazin-2-yl)(isopropyl)amino]butoxy}-N-(methylsulfonyl)acetamide]), its active metabolite MRE-269 and various prostacyclin receptor agonists in rat, porcine and human pulmonary arteries

The study of rare diseases is limited by just that, their infrequency. Pulmonary arterial hypertension (PAH), for example, has a prevalence of 15 cases per million.1 Although there has been an explosion in knowledge of and therapies for this life-threatening disease over the past decade, most of our insight is based on small studies. The first therapy that was approved by the Food and Drug Administration in 1995, intravenous epoprostenol, was based on the results of an 81-patient trial.2 The most recently approved therapy, inhaled treprostinil, in 2009, was based on the results of a 235-patient trial.3 Similarly, our understanding of the natural history of this disease is based on small observational series. Articles see pp 156 and 164 To further our comprehension of rare diseases, we often turn to “registries,” constructed as multicenter cohorts of patients who have the disease with longitudinal follow-up. Despite the inherent limitations of their observational and uncontrolled nature, which also represent strengths, these cohorts are useful to describe and compare patient characteristics, practice patterns, and outcomes. Observations from such registries can generate hypotheses that subsequently form the basis of further studies. Lastly, such cohorts facilitate the study of the prognostic profile of the disease via the derivation and validation of clinical prediction tools. In this issue of Circulation , data from the 2 of the most important present-day registries in PAH give us the opportunity to better understand the prognosis of PAH, its determinants, and outcomes in the current treatment era. Humbert and colleagues4 share data from the French National Registry, in which 354 consecutive idiopathic, heritable, and anorexigen-associated patients with PAH were enrolled from October 2002 to October 2003. They report 1-, 2-, and 3-year survival rates of 82.9%, 67.1%, and 58.2%, respectively. Sadly, despite the many advances in …

CS585 Demonstrates Favorable Selectivity and Sustained In Vivo Action in Preventing Platelet Activation and Thrombosis Compared to Existing IP Receptor Agonists

Selexipag (Uptravi® tablets) is a novel prostacyclin receptor (IP receptor) agonist designed and synthesized at Nippon Shinyaku Co., Ltd., and approved for the treatment of pulmonary arterial hypertension (PAH). Selexipag is converted to MRE-269 in vivo, and the plasma concentration of MRE-269 is maintained at a therapeutic level for a long time. MRE-269 has selective IP receptor agonist activity and exerts vasodilatory and anti-proliferative effects on pulmonary arterial smooth muscle cells. In a study to investigate its vasodilatory effect in isolated rat pulmonary arteries, MRE-269 showed potent vasodilatory effects not only in extralobar but also in small intralobar pulmonary arteries. In a Sugen 5416/hypoxia rat model of PAH, selexipag significantly improved pulmonary artery obstruction, decreased right ventricular systolic pressure, decreased right ventricular hypertrophy and improved survival rate. In a phase II clinical trial for treatment with PAH conducted in Europe, selexipag showed good tolerability with promising efficacy. In an open-label phase II study in 37 patients with PAH in Japan, selexipag significantly decreased pulmonary vascular resistance compared with baseline. In the GRIPHON (Prostacyclin (PGI2) Receptor agonist In Pulmonary arterial HypertensiON) study in 1156 patients with PAH, the largest outcome study ever conducted in PAH, the selexipag treatment group showed a significant reduction in the risk of the primary composite endpoint of death or a complication related to PAH compared with placebo. Selexipag has been shown in clinical trials to prevent the progression of PAH, and is expected to contribute to the treatment of patients with PAH.

Selectivity and Long Action of In Vivo Efficacy of CS585, a Novel Prostacyclin Receptor Agonist, Compared to FDA-Approved Prostacyclin Agonists Iloprost and Selexipag in the Prevention of Thrombosis

Introduction: Selexipag is a first-in-class orally available selective non-prostanoid IP receptor agonist. This review was based on a PubMed search and focuses on the potential role of selexipag in the treatment of pulmonary arterial hypertension (PAH).Areas covered: Selexipag is rapidly hydrolyzed to an active metabolite, ACT-333679. Both selexipag and its metabolite are highly selective for the IP receptor compared with other prostanoid receptors. This selectivity for the IP receptor offers the potential for improved tolerability with selexipag, as side effects (e.g., nausea and vomiting) that might result from activation of the other prostanoid receptors may be minimized. In addition, the selexipag metabolite has a half-life of 7.9 h, thus permitting oral dosing twice daily. Selexipag showed effects on pharmacodynamic end points obtained with right heart catheterization in a Phase II trial in patients with PAH, and is being evaluated in the ongoing Phase III trial (GRIPHON trial, Clinicaltrials.gov NCT01106014).Expert opinion: The signal of a beneficial effect of selexipag on disease progression may become more robust for long term under prolonged exposure. Pending the GRIPHON trial results, selexipag could provide a convenient first-line prostacyclin treatment option for patients with PAH.

(426) - Value of Cardiopulmonary Exercise Testing for Prediction of Outcomes in Ambulatory Patients With Dilated Cardiomyopathy

ABSTRACTIntroduction: Selexipag is the first oral, non-prostanoid, selective prostacyclin receptor (IP receptor) agonist, approved for the long-term treatment of pulmonary arterial hypertension (PAH) in adult patients.Areas covered: This article reviews the clinical pharmacology, efficacy, and safety of selexipag in the treatment of PAH.Expert opinion: Selexipag is the first oral drug that selectively targets the prostacyclin pathway, and has evidence of long-term efficacy and safety. In the global phase 3 study GRIPHON (NCT01106014) in PAH patients, selexipag significantly reduced the risk of the primary composite outcome of morbidity/mortality (M/M). The adverse events in the selexipag group were consistent with the known side effects of prostacyclin, including headache, nausea, jaw pain, and diarrhea. Importantly, selexipag was efficacious and safe irrespective of whether or not patients were already receiving other PAH therapies. With selexipag approval, triple oral combination therapy addressing three important pathways is available for patients with PAH. Selexipag has one major metabolite, ACT-333679, which is also a selective IP receptor agonist, with 37-fold higher potency than selexipag. Pharmacokinetic properties of ACT-333679 permit twice-daily dosing of selexipag, providing a more convenient treatment compared to prostacyclin or its analogs. For patients with moderate hepatic impairment a once-daily regimen is recommended.

Introduction: Pulmonary arterial hypertension (PAH) is a rare disease for which IP receptor agonists provide one of the main classes of treatment. Currently available agents tend to lack receptor selectivity.Areas covered: Four salts of 7-(2,3-di-p-tolyl-7,8-dihydropyrido[2,3-b]pyrazin-5(6H)-yl)heptanoic acid, crystalline forms and compositions of each of these salts, and their use to treat conditions mediated by IP receptor activation, in particular PAH, are claimed. The claimed salts are particularly suited for delivery via inhalation and inhalation devices for their administration are claimed.Expert opinion: This IP receptor agonist represents the first example of selecting a compound to treat PAH that was designed for delivery via inhalation. It indicates Novartis’ desire to establish a broad portfolio of respiratory products.

Pharmacology of the single isomer, esuberaprost (beraprost-314d) on pulmonary vascular tone, IP receptors and human smooth muscle proliferation in pulmonary hypertension

Clinical Course of Patients Transitioned from Another Prostacyclin Pathway Agent (PPA) to Selexipag in SPHERE

Prostacyclin mimetics inhibit DRP1-mediated pro-proliferative mitochondrial fragmentation in pulmonary arterial hypertension

Selexipag (Uptravi®) is an orally active, first-in-class, selective prostacyclin IP receptor agonist. Selexipag was approved recently in the EU for the long-term treatment of pulmonary arterial hypertension (PAH) in adult patients with WHO functional class (FC) II or III as combination therapy in patients insufficiently controlled with an endothelin receptor antagonist and/or a phosphodiesterase type 5 inhibitor or as monotherapy in patients who are not candidates for these therapies, and in the USA for the treatment of PAH (WHO Group I) to delay disease progression and reduce the risk of hospitalization for PAH. Selexipag (200-1600μg twice daily, as tolerated) significantly reduced the risk of the primary composite endpoint of all-cause death or a complication related to PAH (whichever happened first) versus placebo in patients with PAH (mainly WHO FC II or III) in the large, randomized, placebo-controlled GRIPHON study. The treatment effect was largely driven by significant reductions in disease progression and hospitalization for PAH. However, selexipag did not significantly reduce all-cause mortality. Additionally, the observed treatment effect was consistent in a broad range of prespecified subgroups, including treatment-naïve patients and those patients who were already receiving PAH-specific treatment at baseline. Exercise capacity was also improved with selexipag versus placebo. Selexipag was generally well tolerated, with an adverse event profile consistent with other therapies targeting the prostacyclin pathway. Thus, selexipag extends the treatment options available in patients with PAH.

ABSTRACTIntroduction: Prostacyclin is produced in vascular endothelial cells and acts via the IP prostacyclin receptor to cause vasodilation and inhibit smooth muscle cell proliferation and platelet aggregation. Prostacyclin production is reduced in pulmonary arterial hypertension (PAH), and drugs targeting the prostacyclin pathway are one of the pharmacotherapeutic options for PAH.Areas covered: The prostacyclin pathway and drugs that target it are discussed, including synthetic prostacyclin (epoprostenol), prostacyclin analogs (iloprost, treprostinil, beraprost) and selective prostacyclin IP receptor agonists (selexipag). An overview of the development of these therapies, from the earlier agents requiring parenteral administration, through inhaled formulations, to oral products, is provided, together with a summary of data from key clinical trials and registries.Expert commentary: Synthetic prostacyclin and prostacyclin analogs are beneficial for patients with PAH, but they tend to be underused, in part due to the difficulties associated with the administration of parenteral and inhaled formulations. Oral prostacyclin analogs have some limitations with regard to efficacy. The newest agent targeting the prostacyclin pathway, the selective prostacyclin receptor agonist selexipag, is administered orally, and has been shown to reduce a composite morbidity/mortality endpoint. Ongoing studies will help clarify how best to use it in the management of PAH.